Tatiana Maslany and Tom Cullen anchor this drama about trauma, love and the troubles that can bind people together.

“The Other Half” is a film built on withholding. Whether it’s writer/director Joey Klein’s general approach to dispensing key character details or the information that two lovers choose to keep hidden from each other, there’s a pervasive kind of obfuscation that can be at turns refreshing and frustrating. It’s a series of preludes and aftermaths, following an arc of persistent loss and newfound love. But when Klein trusts his actors and leans on the strength of the genuine moments they’re able to create together, the story of Emily (Tatiana Maslany) and Nickie (Tom Cullen) moves beyond the usual constraints of characters with similar pasts.

True to form with the rest of the film’s strongest elements, Nickie and Emily’s relationship has a simple beginning. After making eyes at each other across the room at the café where Nickie works, the two strike up a relationship. At first, Emily seems like the cute-couple opposite designed to offset Nickie’s brooding stoicism. Their flirtation only leads to romance after she draws him from his shadowy apartment and into the sunlight for a breezy double-date.

After a few flirtatious outings, Nickie starts to reveal the emotional weight he’s been carrying: the untimely death of his brother. Not long after, Emily’s behavior quickly belies the fact that her carefree, breezy exterior is also shielding some deep-seated anxieties, in her case stemming from bipolar disorder. Even after she insists that she has her unpredictable mood under control, the two find solace in each other as a way to medicate the source of their sorrows.

“The Other Half” keeps a constant, narrow focus on Emily and Nickie’s individual tumult, but its small concessions to supporting players give just enough context for their troubles. The pair’s relationships with their respective parents show the kind of disconnect that may not be to blame for the state of their psychological well-being, but haven’t helped matters. Still, each conversation with their parents reflects that the tragedies that ripple out from Emily and Nickie’s lives envelop the rest of their family as well. (Special credit to Henry Czerny, who brings a calming presence to one particular dinner table conversation that, had it devolved into histrionics, might have derailed the film.)

Still, even after we’re privy to the basic details of their traumatic pasts, their connection remains built on each other. In this way, Klein keeps their romance balanced, not just a vehicle to cheer up Nickie or to provide Emily’s magical cure. It’s a love that leans on Maslany and Cullen’s chemistry, but weaves their character’s full shared experiences into the fabric of their romance.

“The Other Half”

In turn, Klein uses the camera as a way to reflect their current mental states. A relative stillness presides over Nickie’s early scenes, even as despair encroaches. When Emily’s control finally subsides, Bobby Shore’s handheld camerawork, following her up-and-down rocking, helps bring order to the family chaos. And as the film follows a wide range of emotion, it also travels across the color spectrum, from the pulsating rainbow lights of a club interior to late-night phone calls bathed in a green glow.

Between Maslany’s vibrant presence in Emily’s brighter episodes and the repressed trauma visibly simmering under Cullen’s sullen exterior, their disparate energies help propel the story forward. This isn’t a small-scale romantic dramedy built on crackling dialogue, but Klein does leave room for whimsy. Nickie’s occasional plucking on the ukulele or the flirtatious dances inside apartment living rooms reflect the tiny moments of discovery and bonding, without the usual preciousness that can constrict similar stories of troubled protagonists. (Maslany somehow even makes “Princess Nutbucket” a viable term of endearment.)

Even when certain scenes call on her to play Emily’s unmanageable outbursts to tragic extremes, Maslany brings that same understanding and specificity to Emily’s time closer to middle ground. Nickie’s changes are far less perceptible, but Cullen handles his character’s evolution handily. The vestiges of the emotional lethargy that Nickie carries with him in the wake of his brother’s death still remain, even as Cullen lets a little more of his anxieties surface.

When Klein allows these characters to exist rather than hurtling them towards tragedy, he’s a careful observer of the incremental changes that come with a fortifying love. That the film occasionally toys with or indulges in that tragic action is where it starts to stray. But when it keeps its aims small and its attention narrow, “The Other Half” lands on a simple love story that speaks outside its familiar boundaries.